Best for game intelligence –  Martyn Williams (Wales)

“Martyn was my hero growing up. He was the first person I met at the Blues on my first day in the gym. He was so important to Wales that moves were based around him. For example, we’d call a five-man lineout and move him into the backline. Most backrows smash it up the middle, but we called it the ‘five-man bird option’ and Nugget would end up dinking it over the the defence to create problems. He had real game intelligence. Later in his career most of his turnovers weren’t from him getting smashed on the deck but clever ones, like a contact rip. I’m always getting compared to him. All I say is ‘wait until I get 100 caps and drop a goal’.”

http://www.youtube.com/watch?v=g_7laoQ8B1k

Best for leadership – Richie McCaw (New Zealand) 

“Richie McCaw’s leadership record speaks for itself, over 100 wins as captain in the All Black shirt is just phenomenal! In the nicest possible sense, McCaw is a real nuisance whenever I’ve played against him. He’s very versatile. You can use him at the back of the lineout, as a ball carrier, or of course on the deck. What I’ve noticed about him is when the ball is at the base of a ruck, for a second you’re not sure if it’s out or not, and he’ll gamble and usually get it right – that’s his experience showing. He’s smart, if he’s not making the first up tackle and hitting the carrier second, he’ll make sure he up off the deck quickly to exert some influence on the game. A quality player.”

Best over the ball – David Pocock (Australia)

“If I had to name one player who’s the most difficult to play against, I’d say David Pocock. He’s so strong over the ball, you literally cannot move him. He’s a superb jackaler and as well as being extremely strong, he’s also very flexible. Personally, I do a lot of stretching, with the glutes, hamstrings and groin because you have to get into unusual positions. He’s not the tallest but even so he can ridiculously low. He’s been unlucky with injuries but I have no doubt he’ll come back even stronger.”

Best all-rounder – Francois Louw (South Africa)

“Francois is the biggest No 7 in this list, probably 6ft 3in and over 17st but despite his size he’s very good on the floor, a decent lineout option and he can take contact all day long. He’s very much the modern day South African openside. I played against him in 2010 in one of my first starts for Wales and again for the Blues against Bath, and he’s always been very tricky to play against. Over the last three months, he’d be in my Top 3 in the world.”

Best for footballing skills – Justin Tipuric (Wales)

“Tips has so many skills in his locker. He has a decent You Tube reel that’s for sure. He regularly scores chip and chase tries for the Ospreys! It helps that he played on the Sevens circuit with Wales, where his ball-playing abilities came to the fore. He has a superb engine on him and along with Martyn, those two are unrivalled in world rugby for their skills. At training every day, it’s funny, he stays back with Toby to practice his kicking; to the corners, dinks over the top. It shows his dedication.

Best for raw power – Sean O’Brien (Ireland)

“I can’t leave Sean out of the list. He’s the most powerful on the list by a mile. Obviously he won European Player of the Tear in 2011 as a blindside but on the Lions tour, working closely with him you see how versatile he is. He has really soft hands, can throw accurate miss-passes, create tries and has sweet offloading skills – he’s far from a one dimensional battering ram. He’s worked really hard on his game and taken it on a level.”

Has Sam put forward a decent list. Tell us what you think?

Sam Warburton spoke to us as an HSBC Ambassador at the London Sevens. For more information follow @HSBCrugby. To read our exclusive review of the IRB Sevens Series, pick up the July edition of Rugby World – on sale June 2!